Lift arm assembly for loader vehicles

ABSTRACT

The lift arms of a loader are pivoted to the vehicle at one end and carry a material receiving bucket at the other end, extensible fluid pressure actuated cylinders being connected between the vehicle and lift arms to raise and lower the bucket. To reduce breakage and to facilitate assembly and disassembly without requiring a costly construction, the connection between each fluid cylinder and associated lift arm is formed by a pair of plates disposed one on each side of the lift arm with each plate having a portion extending below the arm. One end of the fluid cylinder is received between the lower portions of the plates and coupled thereto by pivot means. The plates are in turn joined to the lift arms by a pair of removable cross pins which are transpierced through the plates and lift arms at widely spaced points along the length of the arm to distribute stress.

United States Patent 1191 Muellner et al.

1451 May 20, 1975 1 LIFT ARM ASSEMBLY FOR LOADER VEHICLES [73] Assignee:Caterpillar Tractor Co., Peoria, 111.

[22] Filed: Oct. 23, 1973 [21] Appl. No.: 408,667

FOREIGN PATENTS OR APPLICATIONS United Kingdom 403/257 PrimaryExaminer-Allen N. Knowles Assistant ExaminerDavid A. Scherbel Attorney,Agent, or Firm-Phillips, Moore, Weissenberger Lempio & Strabala [57ABSTRACT The lift arms of a loader are pivoted to the vehicle at one endand carry a material receiving bucket at the other end, extensible fluidpressure actuated cylinders being connected between the vehicle and liftarms to raise and lower the bucket. To reduce breakage and to facilitateassembly and disass embly without requiring a costly construction, theconnection between each fluid cylinder and associated lift arm is formedby a pair of plates disposed one on each side of the lift arm with eachplate having a portion extending below the arm. One end of the fluidcylinder is received between the lower portions of the plates andcoupled thereto by pivot means. The plates are in turn joined to thelift arms by a pair of removable cross pins which are transpiercedthrough the plates and lift arms at widely spaced points along thelength of the arm to distribute stress.

3 Claims, 3 Drawing Figures LIFT ARM ASSEMBLY FOR LOADER VEHICLESBACKGROUND OFTHE INVENTION Loader vehicles and certain other forms ofapparatus for manipulating bulk materials customarily have a bucketsupported at one end of a pair of lift arms which are in turn pivoted tothe vehicle. linear fluid motors being connected between the lift armsand'the vehicle to selectively elevate and lower the bucket. Thisconstruction requires that there be a pivot joint between one end ofeach fluid motor and the associated lift arm. In one common form ofjoint, a U-shaped yoke is welded to one end of the rod of the fluidmotor. A lower portion of the lift arm is then received in the yoke anda pivot pin is transpiericed through both the yoke and the lift arm tocomplete the coupling. This arrangement produces concentrated stressesin a small area of the yoke and lift arm and breakage at this region mayreadily occur. To avoid this, particularly in very large highcapacityloaders, it is necessary to use yoke and pivot assemblies ofundesirably massive construction.

In other instances, the connection between the lift cylinder and liftarm has been formed by welding a bracket assembly to the lift arm. Thebracket extends a distance below the arm to receive a pivot axleextending transversely through the bracket and through a sleeve on theend of the fluid motor rod. If of economical size, such a weld is alsoan area of extreme stress concentration and is subject to the samefailure problem discussed above. Further, assembly and disassembly forrepairs is extremely difficult where a welded bracket is employed.

SUMMARY OF THE INVENTION The present invention provides a high strengtheconomical and readily assembled and disassembled coupling between alift arm of a loader or the like and the fluid motor which operates thearm. A pair of plates are disposed one on either side of the lift armand each has a lower portion extending a small distance below the arm.One end of the fluid motor is received between the lower portions of theplates and a pivot connection is provided therebetween. The plates aresecured to the lift arm itself by a pair of removable cross pins whichare widely spaced apart along the length of the lift arm to distributestress forces. In a preferred form of the invention a pair ofsupplementary cross bolts extend between the two plates at the level ofthe lower edge of the lift arm to retain the plates together in theevent that the primary load bearing cross pins should become loose. Thesupplementary cross bolts serve a further purpose of facilitatingpositioning of the lift arm during assembly.

Accordingly, it is an object of this invention to provide for a veryhigh strength but low cost coupling of a loader lift arm to a liftcylinder which coupling may be readily assembled and disassembled andwhich distributes stress forces along the arm rather than concentratingsuch forces at a small limited region thereof.

The invention, together with further objects and advantages thereof willbe better understood by reference to the following description of apreferred embodiment taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawing:

FIG. 1 is an elevation view of the forward portion of a loader vehicleembodying the present invention,

FIG. 2 is a side view of a portion of the apparatus of FIG. 1 furtherillustrating the coupling between a lift arm and fluid motor thereof.

FIG. 3 is a plan view of the structure shown in FIG. 2.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawing andmore particularly to FIG. 1 thereof, there is shown a portion of aloader vehicle 11 of the type having a bucket 12 carried at the forwardend of lift arms 13. The lift arms 13 which have a slight S-curvature inthis particular example are coupled to the body 14 of the vehicle by afirst pivot connection 16 which enables the forward end of the lift armtogether with bucket 12 to be lowered whereby the bucket may receivematerial upon forward motion of the vehicle and which enables the liftarms and bucket to be elevated for the purpose of carrying the materialto another area where the material may be dumped. In most loaders, thebucket 12 is coupled to the forward end of the lift arms by anotherpivot connection 17. Tilt linkage 18, including an extensible andcontractible fluid operated tilt cylinder 19, is provided to enableselective pivoting of the bucket relative to the lift arms. Suitabledetailed construction for the loader vehicle 11, bucket 12 and tiltlinkage 18 are known to the art and accordingly will not be furtherdescribed.

In order to selectively raise and lower the lift arm 13 and thus thebucket 12, lift cylinders 21, which may be extensible and contractiblehydraulic fluid motors, each have a head end coupled to the body 14 of avehicle at a pivot connection 22 and extend upwardly and forwardlytherefrom towards the underside of a central portion of an associatedone of the lift arms 13. Referring now to FIGS. 2 and 3 in conjunction,the coupling 23 between each lift arm I3 and lift cylinder 21 is formedin part by a pair of plates 24 of substantially triangular configurationdisposed one on each side of a central portion of the associated liftarm 13. Each such plate 24 has one corner 26 extending below the levelof the adjacent portion of the lift arm 13. The upper end of the liftcylinder rod 27, including a transverse sleeve 28 carried thereon, isreceived between the lower portions 26 of the plates. A transverse pin29 ex tends through plate portions 26 and sleeve 28 to form a pivotconnection between the cylinder 21 and the lift arm.

Plates 24 are arranged so that a broad edge 31 thereof extends along asizeable portion of the length of the central section of lift arm 13 toenable a pair of widely spaced apart cross pins 32 to be transpiercedthrough the plate and the lift arm to secure the plates and the lift armtogether. This divides the stress at the point of attachment to the liftarm between spaced apart points thereon thereby reducing the risk offailure under heavy loading. Cross pins 32 are preferably of the formdescribed in copending Application Ser. No. 318,516 of Robert F.Shankwitz et al., now US. Pat. No. 3,841,771 filed Dec. 26, 1972, andentitled Tapered Hinge Pin Assembly and Removal Means. Pin assemblies ofthis kind are provided with bolts 33 in each end which may be tightenedto axially compress the assembly and thereby cause radial expansion ofthe end portions of the assembly which wedges the pin 3 tightly into theadjacent structure. the pin assemblies being disengageable by reverseturning of the bolts.

A pair of spaced apart supplementary cross pins formed by bolts 34extend between the plates 24 immediately below the undersurface of thearm 13. Bolts 34 serve to hold the plates 24 in operative position inthe event that the primary loan bearingmembers. the cross pins 32,should become loosened in operation-Bolts 34 when positioned asdescribed above also facilitate assembly and disassembly of the coupling23 by serving as a means for positioning the lift arm 13 relative to theplates 24 during installation or removal of the cross pins 32.

While the invention has been described with respect to a singleembodiment, it will be apparent that modifications are possible and itis not intended to limit the invention except as defined in thefollowing claims.

What is claimed is:

1. Lift arm mechanism for a loader vehicle which has an elevatablebucket for receiving and lifting material comprising:

a lift arm having first and second ends and having an intermediatesection between said ends,

first pivot means for coupling said first end of said lift arm to saidvehicle and providing for raising and lowering of said second endthereof,

means for attaching said bucket to said second end of said lift arm.

a pair of plates disposed adjacent said intermediate section of saidlift arm each being at a separate side thereof and each having a lowerportion extending below said lift arm,

a linear fluid motor having one end pivotally connected'to said vehicleand having an opposite end extending between said lower portions of saidplates,

second pivot means coupling said opposite end of said fluid motor tosaid lower portions of said plates,

a pair of removable cross pins each being transpierced through saidplates and said intermediate section of said lift arm at spaced apartpositions along said intermediate section of said arm with one of saidcross pins being situated closer to said first end of arm than saidsecond pivot means and the other of said cross pins being close. to saidsecond end of said arm than said second pivot means whereby stressforces are divided between spaced apart regions of said lift arm. and apair of spaced apart supplementary cross pins extending between saidlower portions of said plates below said lift arm.

2. The combination defined in claim 1 wherein said cross pins are of theform having bolt means for axially compressing said pins to therebycause radial expansion of said pins to wedge said pins in said plates.

3. The combination defined in claim 1 wherein said supplementary crosspins extend between said plates immediately below the lower surface ofsaid lift arm.

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1. Lift arm mechanism for a loader vehicle which has an elevatablebucket for receiving and lifting material comprising: a lift arm havingfirst and second ends and having an intermediate section between saidends, first pivot means for coupling said first end of said lift arm tosaid vehicle and providing for raising and lowering of said second endthereof, means for attaching said bucket to said second end of said liftarm, a pair of plates disposed adjacent said intermediate section ofsaid lift arm each being at a separate side thereof and each having alower portion extending below said lift arm, a linear fluid motor havingone end pivotally connected to said vehicle and having an opposite endextending between said lower portions of said plates, second pivot meanscoupling said opposite end of said fluid motor to said lower portions ofsaid plates, a pair of removable cross pins each being transpiercedthrough said plates and said intermediate section of said lift arm atspaced apart positions along said intermediate section of said arm withone of said cross pins being situated closer to said first end of armthan said second pivot means and the other of said cross pins beingcloser to said second end of said arm than said second pivot meanswhereby stress forces are divided between spaced apart regions of saidlift arm, and a pair of spaced apart supplementary cross pins extendingbetween said lower portions of said plates below said lift arm.
 2. Thecombination defined in claim 1 wherein said cross pins are of the formhaving bolt means for axially compressing said pins to thereby causeradial expansion of said pins to wedge said pins in said plates.
 3. Thecombination defined in claim 1 wherein said supplementary cross pinsextend between said plates immediately below the lower surface of saidlift arm.